Too often, the needs of an increasing population are at odds with the needs of the environment. More people means more mouths to feed. That, in turn, means that we need more land for agriculture. Since there’s only a finite amount of dry land on our planet, we’re increasingly converting forests and jungles into farms and pastures. We may be working towards better food security, but to the detriment of biodiversity and conservation.

Writing in this week’s issue of Science Magazine, Paul C. West of the University of Minnesota and colleagues identify what they call “global leverage points”: a small list of regions and actions that humanity should focus on to both improve global food security while simultaneously decreasing the negative impact of agriculture on the environment. “We find that a relatively small set of places and actions could provide enough new calories to meet the basic needs for more than 3 billion people, address many environmental impacts with global consequences, and focus food waste reduction on the commodities with the greatest impact on food security,” they write.

West and his group combined data on the 16 highest-calorie crops plus cotton (because it has intensive water and nutrient use). Those 17 crops cover nearly 60% of global agricultural land. They contribute 86% of the world’s crop-derived calories. Together, they account for 95% of irrigated area, 92% of water consumption, and some 70% of all nitrogen and phosphorus application (via fertilizers). Taken together, agriculture accounts for more than a quarter of our planet’s greenhouse gas emissions, which includes not just CO2 increases thanks to deforestation, but also methane emissions from livestock.

It sounds like a dire situation, but West and his colleagues suggest that focusing on increasing efficiency and decreasing waste in a few key areas could mitigate quite a bit of the environmental destruction wrought by agriculture.

For example, most of the excess nutrients that enter into the environment come from China, India, and the United States. Crops do need fertilizers to grow, but nutrient runoff is a critical source of pollution in freshwater and coastal ecosystems. The excess nutrient application is the difference between the application of nutrients through fertilizer and removal through plant harvesting. Whatever is left after harvest sinks into the ecosystems, and that amounts to 60% of nitrogen and nearly 50% of phosphorus. That means that the majority of nutrients applied are wasted. More judicious application in those regions would have a disproportionate affect on the planet.

The researchers then compared water use to average annual precipitation in agricultural areas. The regions that use the most water despite their status as “precipitation-limited areas” include Pakistan, China, the United States, and especially India. Focusing on more efficient water delivery systems in these areas could also help quite a bit.

Then there’s the issue of calorie dilution. “Although crops used for animal feed ultimately produce human food in the form of meat and dairy products, they do so with a substantial loss of caloric efficiency,” writes West. If the crops currently used for animal feed and for other non-food uses (such as biofuel) were instead directly consumed by hungry folks, we could feed an additional 4 billion people.

Naturally, we can’t convince everyone to become vegetarian, but the United States, China, Western Europe, and Brazil use the most crop-derived calories on non-food uses. The researchers acknowledge that “cultural preferences and political obstacles create large challenges to reducing meat as well as over-consumption,” particularly in those wealthier nations.

Even worse is that approximately 30 to 50 percent of food produced is ultimately wasted. Wasting beef is especially troubling. Throwing away one kilogram of boneless beef is twenty four times worse than wasting one kilogram of wheat. That’s because the conversion of crops to animal protein is extremely inefficient. Wasting pork and poultry are somewhat less severe, but still significantly more damaging than wasting crops. For comparison, the average person in India wastes fewer than three calories each day, primarily through pork and vegetables. Americans can waste as much as 290 calories each day in beef. Put another way, Americans waste 7-8 times as much farmland as Indians do.

Reducing food waste in the major crops (wheat, rice, and vegetables) and meats (beef, pork, and poultry) in the United States, China, and India alone could feed an extra 413 million people each year. “Small changes in the consumption and waste of animal products could have a large effect on available calories,” write the researchers.

These solutions are not simple or easy, but by highlighting areas in which the biggest differences can be made to food security and to conservation, the researchers hope to provide NGOs, foundations, governments, citizens’ groups, and businesses a roadmap to balancing agriculture and environment. – Jason G. Goldman | 18 July 2014